if you have any apps that disable multitasking for ios4 like myos then your dock icons will grey out or vanish.
you cant disable multitasking on 5.0.1 yet...as far as i know.
check your backed up apps to see if any include disabling multitasking

if you have any apps that disable multitasking for ios4 like myos then your dock icons will grey out or vanish.
you cant disable multitasking on 5.0.1 yet...as far as i know.
check your backed up apps to see if any include disabling multitasking

Multitasking can be disabled with Springtomize 2, and although potentially buggy, Backgrounder and tweaks via Winterboard.